Vehicle manufacturers attempt to reduce the weight of the vehicles in order to enhance the fuel economy of the vehicle. Often the reduction in weight compromises the strength of component parts. Recently, regulations, such as ECE17 and Federal Motor Vehicle Safety Standards (FMVSS), such as FMVSS202A, have mandated a stiffer component structure for vehicle seats and greater energy absorption for associated seat headrests.
Recent components such as seat backs comprising a plastic blend of polycarbonate and acrylonitrile butadiene styrene (PC/ABS) have increased the cost of seat backs as well as increased the weight of the blowmolded polyethylene seat backs that they replaced. In other situations, headrests formed of polyurethanes foam failed the vertical height volumetric compression test as well as the deformation retention test.